The present invention relates to character generating systems.
As output apparatus for a computer, an electronic printer and a character display are widely utilized. Various character generating systems therefor are known, including a charactron system wherein a character disk is placed in a cathode-ray tube and characters are generated by applying an electron beam thereto, a monoscope system wherein characters are prepared for scanning on the monoscope and are converted to image signals for display projection on the cathode-ray tube, a dot matrix system wherein characters to be displayed are divided into dots and thus displayed, and a stroke system wherein patterns of characters are stored in the form of vectors and are so formed for display. Among these systems, the dot matrix system, for example, inputs to the character generator the output from an information source--such as a central processing unit--and generates character signals there stored as a pattern of dots. The system for forming dot-based characters includes a character line scanning system wherein plural characters contained in the same line are scanned character line after character line, and a head scanning system wherein a head having plural dot generating elements successively forms the characters one after another.
It is important to realize that the range of characters to be displayed on the output apparatus can include katakana and Chinese characters as well as those of the Roman or English alphabet. In the case of the alphabet, one known displaying method, as shown in FIG. 1, provides for uppercase and lowercase letters (except j) to be displayed in an array defined by 32 lines longitudinal .times. 24 dots lateral, while a lowercase letter j is displayed with 42 lines longitudinal .times. 24 dots lateral. A space equivalent to 6 dots is allowed between each letter in the lateral direction; between each character line, a space equivalent to 22 lines is provided for uppercase letters and a space equivalent to 12 lines is placed between uppercase letters and the 5 lowercase letters g, j, p, q and y (hereinafter referred to as the "specific lowercase" or "descender" letters). According to this display method, 4 of the specific lowercase letters (excluding j) can be properly displayed by downwardly shifting them a distance equivalent to 10 lines so that the memory area needed to store such a letter is 32 lines longitudinal .times. 24 dots lateral. For the letter j, on the other hand, a memory area of 42 lines longitudinal .times. 24 dots lateral is required. As a consequence, accommodation of the lowercase letter j requires that the memory area for all of the letters be dimensioned to support a dot array of 42 lines longitudinal .times. 24 dots lateral, even though insofar as the remainder of the letters of the alphabet are concerned, the reserved memory area for 10 lines (42 lines - 32 lines) longitudinal .times. 24 dots lateral will not be used and is therefore wasted. Particularly with respect to character generators with high resolving power--as in the present example wherein a letter of the alphabet is displayed with 32 lines longitudinal .times. 24 dots lateral--the area corresponding to 10.times.24 dots is substantial and it is therefore necessary to utilize a memory element having a relatively large capacity. In order to avoid such a waste of memory area, one might consider storing even a lowercase letter j in a memory area of 32 lines longitudinal .times. 24 dots lateral. However, when an English or Roman letter is displayed by a conventional character generator with the use of character signals thus stored, the displayed letter has an unnatural appearance and the purpose and advantage of using a high resolution display method is lost. It is, for example, possible in such circumstances that an error in reading will be made due to illegibility of the displayed letter, and the noted arrangement has not therefore been regarded as perfectly satisfactory as an output apparatus for a computer or the like.